YAQS

YAQS (Yet Another Queue System) is a Node.js module to manage job queues using Redis.

YAQS manage any number of queues, any number of servers and any concurrency per server per queue.

Installation

npm install yaqs

Client

To use YAQS you need to create a client:

var client = require('yaqs')(opts)

You can use this client to create, use and remove queues.

Options

• prefix (default='yaqs'): A prefix for Redis keys
• redis (default={}): Configuration to connect to Redis
  • port (default=6379): Redis port
  • host (default="localhost"): Redis host
  • pass (default=undefined): Redis password
• defaultConcurrency (default=1): Default concurrency
• defaultTimeoutOnStop (default=2000): Default timeoutOnStop in ms (timeout before force-killing a queue)
• defaultPriority (default=client.PRIORITY.NORMAL): Default priority when we create job without priority option
• defaultRetry (default=0): Default number of retry before giving up on a job
• defaultRetryDelay (default=-1): Default retry delay in ms; values lower than 0 means direct retry.
• defaultTimeout (default=-1): Default timeout in ms

Usage

// An object of constant priorities
client.PRIORITY;

// Create queue with a name and some options
client.createQueue(name, opts);

// Call queue.stop() on all queues
client.stopAllQueues(function(err) {});

// Get stats of all queues with this prefix in Redis
// Stats for the queue 'test' are in stats.test
client.stats(function(err, stats) {});

Queue

var queue = client.createQueue(name, opts);

Options

• concurrency (default=client.defaultConcurrency): Concurrency for this queue in this server
• timeoutOnStop (default=client.defaultTimeoutOnStop): When stoppping the queue, maximum amount of time in ms to wait before force-stopping workers. If the timeout is less than or equal to 0, no limit is enforced.
• defaultPriority (default=client.PRIORITY.NORMAL): Default priority for new jobs
• defaultRetry (default=0): Default retry for new jobs
• defaultRetryDelay (default=-1): Default retry delay in ms for new jobs
• defaultTimeout (default=-1): Default timeout in ms for new jobs

Usage

// Start processing jobs,
// Callback can get an error if unable to retrieve jobs from Redis.
queue.start(function(err) {});

// Set the function used to process jobs.
// Can be hot-swapped while the queue is working
queue.setWorker(function (job, cb) {});

// Create a job with data and somes options (optional)
// This job needs to be saved to be processed
var job = queue.createJob(data, opts);

// Stop processing jobs
queue.stop(function(err) {});

// Stop processing jobs and remove all jobs
queue.remove(function(err) {});

// Get stats for this queue
// stats.pending = number of pending jobs
// stats.processing = number of processing jobs
// stats.total = total number of jobs added to this queue
queue.stats(function(err, stats) {});

// Remove stucked processing jobs
queue.cleanProcessingStuckJobs(function(err) {});

Events

queue.on('error', function(err) {});                // When an error occured
queue.on('start', function(queue) {});              // When we start the queue
queue.on('stop', function(queue) {});               // When we stop the queue
queue.on('remove', function(queue) {});             // When we remove the queue
queue.on('empty', function(queue) {});              // When a queue has no new jobs to process

queue.on('job.completed', function(job, data) {});   // When a job complet
queue.on('job.failed', function(job, err) {});      // When a job fail
queue.on('job.timeout', function(job) {});          // When a job timeout

Example of worker function

function workerFunction(job, cb) {
    // Use job.data to do something
    console.log(job.data.foo);

    // Return an error for event 'job.failed'
    cb(new Error("An error"));

    // Return some data for event 'job.complete'
    cb(null, {foo: 'bar'});
}

queue.setWorker(workerFunction);

Job

var job = queue.createJob(data, opts);

Options

• priority (default:queue.defaultPriority): Priority for the job, greater is better. Use client.PRIORITY values (VERY_HIGH, HIGH, NORMAL, LOW, VERY_LOW)
• timeout (default:queue.defaultTimeout): Timeout of the job in ms. If the job is not finished after the timeout, it is considered finished (although the job is not killed, it is your responsability to ensure you're not leaking resources). If the timeout is less than or equal to 0, it is not taken into consideration. A job.timeout event is sent on the queue.
• retry (default:queue.defaultRetry): number of retry to use if the worker returns an error.
• retryDelay (default:queue.defaultRetryDelay): delay in ms between two retry

Usage

// Set job's priority
job.setPriority(priority);

// Save job in redis for processing
job.save(function(err) {});

// Remove job from pending list
job.remove(function(err) {});